A system on chip may have all components of a computer and/or other electronic system into a single integrated circuit chip. The system on chip may contain any of digital, analog, and mixed-signal functions (e.g., as well as a radio-frequency function) all on one chip. The system on chip may have a microcontroller, a microprocessor, a DSP core, a memory block, a timing source, a peripheral, an external interface, and/or a power management circuit. The various hardware parts of the system on chip may be connected by buses (e.g., an AMBA bus, an APB, etc.). The system on chip may also include a number of software modules embedded on the system on chip to control operations of the various hardware parts.
The system on chip may communicate with an external device (e.g., a sensor device) to monitor the external device and/or report a data obtained by the external device to a controller (e.g., a program able logic controller) through a network. To monitor the external device, the system on chip may stay on continuously and/or periodically wake itself up according to a set schedule. When the system on chip is operating in a wireless mode, the continuous operation of the system on chip may quickly drain a power source (e.g., a local battery) of the system on chip.
Although the periodic wake-up of the system on chip to do the monitoring may reduce the drain of the power source to some degree, it may still exhaust the power source rather quickly so as to require a frequent replenishment of the power source. Aside from the drainage of the power source, there may exist a danger of losing the data (e.g., important) which should have been reported to the controller if the system on chip is disabled due to the exhaustion of the power source.